Climate change reinforces the intense atmospheric rivers that batter California

Las squalls that reach the west coast of the United States, are getting stronger. This is shown by the data that different research centers have been collecting over the last decades. California has experienced one of those great storms recently between the end of 2022 and the beginning of this new year.

It has been a squall force that was intensified by a process of explosive cyclogenesisbut which has also been fed by what is known as a ¨Atmospheric River¨. These are essentially rivers of water vapor in the sky carried by strong winds in lower levels of the atmosphere.

California frequently experiences them during the winter months, coinciding with the rainy season. These rivers are also recorded in many other areas of the world, even in Spain affected us during the final stretch of autumn and beginning of winter.

A deep storm nearing the coast of Canada and the United States on October 21, 2021. Image: NOAA

A term relatively unknown to many.

Meteorology experts began to use the terminology ¨Atmospheric River¨ more frequently in the early 1990s 2010.

It was all thanks to satellite images higher resolution, showing their formation in remote regions of the ocean. Even for the public not specialized in the matter, it is a term that is still quite unknown.

Atmospheric Rivers reach more than 3,000 kilometers long and 800 kilometers wide

Atmospheric Rivers can grow up to 3,500 kilometers long, and span some 800 kilometers wide. They also extend vertically to about 3 kilometers high when they reach the western shores of the continents.

On average they dump much more rain than a typical thunderstorm on the west coast of the United States. transport in the form of water vapor 25 times the water flow of the Mississippi River when it empties into the Gulf of Mexico, a lot of water.

Rivers of water in the air more and more mighty

you are big water-laden storms They can produce devastating floods, including the most intense some areas have experienced in a century.

They can occur in nuclei, which means the arrival of a series of storms, as if they will all arrive rolling one after the other on a conveyor belta.

Several times a year they strike the western shores of the United States, Canada, Europe, Africa, South America and New Zealand. But they are not always destructive, sometimes they bring beneficial rain to dry regions. They can also positively increase snow cover and help replenish both natural and man-made water reserves.

However, it is difficult to anticipate more than a few days where exactly the core of the Atmospheric River will make landfall. being so big, they can be fickle because there are numerous factors that can affect its progression.

Both ocean surface temperaturesLike the cold air pockets in height, condition its position and intensity.

Representation of an atmospheric river carrying water vapor from thousands of kilometers southwestern California to its coast. Image: NOAA

Stronger and more frequent Atmospheric Rivers are expected in a warmer climate

Places like California, they depend a lot on water that contribute these Atmospheric Rivers. Mainly because provide water and snow fundamental for the supply, and the biodiversity of the region.

They can also pose a problem when, as is happening at the beginning of 2023, they generate intense and continuous rainfall.

A new NOAA study published in the magazine Climate Dynamicsuses data generated by regional climate models to study and understand the behavior of Atmospheric Rivers.

The results suggest that the Climate change probably is altering them and will further alter them in ways that make water management in the region more difficult.

apart from impact that on these Atmospheric Rivers may have the natural variability of the climate with phenomena such as The child or the girl among others, there are some related to the human activity that change their behavior.

Experts point out that anthropogenic global warming, whether from air masses or ocean water, is also transforming them.

On one side water vapor increases coming from the ocean surface. On the other, it heats up the airincreasing its capacity to transport more water vapor just as these great rivers do in the atmosphere.

As the planet warms, storms fed by intense Atmospheric Rivers are becoming more intense in California
The California coast suffers the impact of the intense Atmospheric Rivers of this century through intense rains and strong waves.
Photo: USGS

The future scenario of Atmospheric Rivers in California

The mountains of the range Sierra Nevada they are an irreplaceable component of California’s current water system. The snow Cape in the high Sierras it acts as a giant reservoirreleasing clean water during the snowmelt season.

The sixty percent California water supply originates in the Sierras higher elevation. More than 75 percent of Californians drink water generated by the snow that accumulates in that mountain range.

It has also been observed that the snow behavior dynamics accumulated has changed over the years and their fusion begins much earlier than decades ago.

Not only that, more than half of the climate model calculations in the recent NOAA study have shown that the Sierra Nevada snowpack will experience a significant decrease in precipitation by 2100.

Snow cover in the Sierra Nevada mountain range in California will experience a significant decrease by 2100

While that happens in the mountains, the great arid basin of southern California could benefit from a increased precipitationgenerating a generally more humid scenario in an area that is now more arid.

In any case, what is also within the future climate scenarios is that the nature of the precipitation will change. They wait heavier rainfallmore continuous but at the same time more intermittent on longer time scales.

As usual with the new sign of Climate changethe lime of this corner of the planet that many others depend on and much of the water will live in a scenario of frequent meteorological fluctuations.

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